A columnist wary of police discretion in enforcing a teen curfew:
The County Council is considering an ill-conceived curfew for kids under 18 after a flash-mob gang fight … At the jam-packed hearing, Montgomery officers assured curfew skeptics and opponents that they weren’t out to lock up the kids coming home late from jobs or Harry Potter premieres. … So, how exactly do they plan on telling the good kids from the bad ones? I’m pretty sure most kids will forget their government-issued, GOOD KID ID badge every time they go out. A government-imposed curfew opens the door to harassment and profiling when what we need is policing of criminals and parenting of kids. (more)
A police officer responds:
Today’s Montgomery County police are part of one of the first generations of Americans to have grown up “color blind,” or for that matter, blind to all bias. ….
We are able to tell the bad kids based on their behavior. It’s the kids who come to hang out but never spend a dime at area businesses. The ones dropping the “F-bomb” so loud that you cringe when you’re walking by with your family. The ones who comment on the appearance of your daughters, walking behind them and taunting with comments so crude it would make a sailor blush. The ones who end up staying late, wanting to fistfight kids from other neighborhoods because of some street name or boundary line that is important only in their minds. The ones who follow you as you walk out of Silver Spring into the adjoining neighborhoods, snatching your iPhone and running to the Metro to get home. (more)
This exchange nicely illustrates the conflict between the ideals we want law to embody, of police just enforcing a clearly specified “law,” and the real messy peace-keeping tasks police actually perform. This police officer clearly expects to use lots of discretion in deciding who to harass. While it is not officially illegal to shop without buying, or to use swear words, or to care about neighborhood lines, he’d use those as indicators about whom to harass. He’d probably on average mostly harass kids that locals dislike, though he’d also probably act on personal biases and preferences. And I’ll bet that among police, the only unusual thing about his attitude is that he published it. Police must give lip-service to being “unbiased,” and local citizens will pretend along with them, if that’s what it takes to keep the peace.
I don't really see how curfews would affect flash mobs at all. If they put ankle bracelets on all teenagers, and arrested every single teenager out after curfew it would only result in flash mobs being restricted to daylight hours. From the videos I have seen, several happened during daylight anyway. Curfews seem to be little more then doing something for the sake of doing something rather then solving any problem.
I haven't been closely following the incidents of violent "flash mobs", but it does seem like the kind of thing conventional clean-hands law enforcement would have trouble with. They would either need to have a presence anywhere an attack might happen (and thin spreading might result in being overwhelmed) or have very fast response times, unlikely since it tends to take too long for victims to even contact police.
This website has been maintaining a list of news stories on such incidents, and this racist blog has a heavy focus on them.